Cache validity rules in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of cache validity rules in nginx?

Cache validity rules tell nginx when to keep or discard cached content to ensure users get fresh and correct data.

beginner

Which nginx directive controls how long cached content is considered valid?

The proxy_cache_valid directive sets the time period for which cached content is valid.

intermediate

How does nginx decide to serve cached content or fetch new content?

Nginx checks cache validity rules like expiration time and HTTP headers to decide if cached content is fresh or needs updating.

beginner

What happens if cached content is expired according to cache validity rules?

Nginx will fetch fresh content from the origin server and update the cache with new data.

intermediate

Explain the role of HTTP headers like Cache-Control and Expires in nginx cache validity.

Nginx uses these headers to understand how long content should be cached and when it should be considered stale.

Which directive sets the cache validity duration in nginx?

A proxy_cache_methods

B proxy_cache_path

C proxy_cache_key

D proxy_cache_valid

The proxy_cache_valid directive defines how long cached responses are considered valid.

What does nginx do when cached content is expired?

A Serve the expired content anyway

B Delete the cache and serve an error

C Fetch fresh content from the origin server

D Ignore cache and always fetch new content

Nginx fetches fresh content to replace expired cache entries.

Which HTTP header helps nginx decide cache validity?

A Cache-Control

B Content-Type

C User-Agent

D Authorization

Cache-Control header tells nginx how long to cache content.

If no cache validity rules are set, what is the default nginx behavior?

A Cache forever

B Never cache content

C Cache for 10 minutes

D Use origin server headers to decide

The proxy_cache_valid directive is required to define cache validity; without it, nginx may cache content based on origin headers but does not set explicit validity durations.

What does the proxy_cache_valid 200 10m; directive mean?

A Cache only 200 OK responses for 10 minutes

B Cache 200 responses for 10 seconds

C Cache all responses for 10 minutes

D Cache 404 responses for 10 minutes

It caches only HTTP 200 responses for 10 minutes.

Describe how nginx uses cache validity rules to manage cached content freshness.

Think about how nginx decides when to keep or update cached data.

Explain the impact of setting incorrect cache validity rules in nginx.

Consider what happens if cache is too short or too long.